Technical Field
The present disclosure relates to medical devices and more particularly to the process of anchoring medical catheters to the skin of human patients to prevent movement of a catheter after insertion into the body. The catheter anchors described may also be used in a similar fashion for veterinary use.
Discussion of the Related Art
One of the most common medical procedures performed each year is the insertion of catheters into the body for the purpose of delivering fluids to or extracting fluids from a specific part of the body and/or extracting air from a specific part of the body. Examples of catheters include but are not limited to central venous catheters (CVC) which deliver fluids intravenously to a vein typically in the chest, neck, or groin; peripherally inserted central catheters (PICC lines) which deliver fluids intravenously typically in the arms; chest tubes which extract fluids and/or air from the chest cavity; gastrostomy tubes (G-tubes) which deliver fluids to the stomach; jejunostomy tubes (J-tubes) which deliver fluids to the jejunum; and Hickman catheters which are used in chemotherapy and hemodialysis. An additional type of catheter uses a wire to deliver current to a specific part of the body. A trans-venous pacemaker wire that is placed temporarily into the heart is an example of a wire-based catheter that delivers current to the heart instead of fluids. Each of these and other catheters and lines that enter into the body should be stably anchored to the patient's skin so that their precise placement into the vein, heart, chest cavity, stomach, jejunum, etc. is not disturbed by movement of the patient so that the catheter or line can achieve its intended delivery or extraction purpose. Furthermore, it is important that the catheter or line remain in its inserted location to prevent damage to the patient including tearing of the skin, dislodging of the catheter, rupturing of the vein, accidental removal, or other consequential damage from the unintended movement of the catheter. For this purpose, typically a catheter anchor is attached to the patient's skin near the catheter or line insertion site, and the catheter or line is mechanically tethered to this anchor to prevent the catheter or line from being moved or disturbed.
A common methodology for anchoring the catheter or line to the patient's skin is the use of a catheter anchor that can be sutured to the patient's skin. These catheter anchors come in various sizes and configurations to accommodate catheters of different diameters and some are affixed directly to the catheters themselves, but they typically work in the same fashion. They are typically applied by a physician due to the skill needed to suture them to the patient. In typical use a physician will insert a catheter into a patient to a particular depth or position. Next the physician will place a form-fitting non-slip pliable sleeve typically made of silicone around the catheter near the insertion point into the body. The physician then places, for example, a hard plastic cap that is keyed to the silicone sleeve over the sleeve. This cap typically has two holes that are parallel to the patient's skin when in position. Once the cap is in position, the physician will suture the cap using a straight or curved exposed needle and non-dissolvable suture thread to the patient's skin using the two holes in the cap. The physician should be careful not to penetrate the skin too deeply so as not cause excessive bleeding, nerve damage, or other physical damage to the patient but should also penetrate deeply enough to securely anchor the catheter. The suturing process involves inserting the needle through the skin on each side of the cap, drawing the suture threads through the skin, and then tying the loops of thread to each side of the catheter via their respective holes. Due to the dangers associated with the open needle, it is critical that the patient remain still during the insertion procedure. The process of attaching the catheter to the patient's skin in ideal circumstances takes approximately 3 minutes after the catheter has been properly positioned. If a patient is not still during the procedure, then the suturing process can take considerably longer. After the physician completes the suturing process, medical adhesive tape is then applied over the sutured catheter anchor to further secure the catheter anchor and to cover the puncture wounds made by the needle to reduce the risk of contamination and subsequent infection. Once the catheter anchor has been sutured to the patient, it is difficult to move or adjust the catheter. The exact position of the catheter is almost always verified by x-ray. If the physician needs to reposition the catheter at all (which happens frequently), then the physician has to cut and remove the sutures, remove the catheter anchor cap, reposition the catheter, and repeat the entire suturing process as described above. This results in additional wounds in the patient's skin and tissue, consequently multiplying the risk of infection or the aforementioned other risks to the patient. A catheter anchor as described can usually remain in place on a patient's skin for a limited time (typically up to a week). During that time, the wound area created by the needle punctures and the catheter insertion site must be cleaned as frequently as necessary with a disinfecting cleaning solution such as Betadine to reduce the risk of infection to the patient. Millions of catheters of all different sizes and types are inserted into patients in the US every year, most requiring at least one catheter anchor per insertion.
There are several safety risks to both the physician and the patient involved with the insertion of a typical sutured catheter anchor. One risk is a needlestick injury to the physician. If the physician who is wearing protective surgical gloves comes in contact with the patient's blood via puncturing of the physician's skin by the infected needle, the physician may contract any number of diseases born by the patient. In some cases this may lead to a chronic or life-threatening disease including HIV infection or Hepatitis which are passed from one human to another by blood to blood contact. The risks associated with a needlestick injury can be very serious. In many hospitals, it is a requirement that a physician undergo expensive testing for possible infection whenever there is a contaminated or suspected contaminated needlestick injury. The risk of a needlestick injury is significant when using an unprotected needle even when the patient is completely still. If a patient is agitated or unstable, the risk of a needlestick injury is greatly increased due to the unpredictable motion of the patient. A patient can also be subject to a needlestick injury if the physician unwittingly punctures his or her skin during the suturing process and then contaminates the patient with the infected needle.
Needlestick injuries have become a very serious health risk for medical professionals. According to the CDC, more than 800,000 needlestick injuries take place in the US alone each year, and this number does not reflect the numerous needlestick injuries that go unreported. Of these 800,000 needlestick injuries, more than 380,000 happen to hospital-based medical personnel, resulting in more than 1,000 cases of serious infections to physicians or other medical practitioners every year.
Therefore, any measure that can reduce needlestick injuries is both potentially lifesaving and highly cost effective. Due to the serious risks associated with needlestick injuries including blood-borne infections of fatal and incurable diseases, Congress enacted the US Needlestick Safety and Prevention Act which mandates the use of safer alternative methodologies to conventional needles whenever it is possible to do so. Insurance companies also follow the same safety guidelines.
Another significant risk to the patient during and after the insertion of a sutured catheter anchor is infection. While the physician takes great care not to contaminate the needle or the wound sites made by the needle, infections can and do enter the patient's bloodstream via the wound sites. This can lead to significant complications for the patient depending on the type of infection and the patient's health, and in some cases may become life-threatening or lead to death. Reducing infection is important during the insertion of any catheter and catheter anchor. Any time a needle enters, exits, and then re-enters the skin, the risk of contamination increases, and consequently the risk of infection to the patient increases. Additionally, each time a needle enters the skin, a new wound site is generated; and with each additional wound site, the risk of infection increases. Therefore, the drawing of the exposed needle or suture thread through the patient's skin and out again increases the risk of infection to the patient by both increasing the number of wound sites and by potentially drawing contaminants into the patient's skin which can come in contact with the patient's bloodstream. This can even occur when the suturing process is conducted in a clean hospital environment.
The risk of damage done by the insertion of the needle is yet another safety issue. Even a skilled physician can damage the patient's skin, underlying tissue, nerves, blood vessels, or worse if the patient moves unexpectedly during the time that the needle has penetrated the patient's body. The needle insertion typically is only done between a depth of 3 and 5 mm below the surface of the skin (depending on the insertion location on the body) to reduce bleeding and nerve pain or damage which takes great care and skill by the physician. Given the typical time that is needed to suture a catheter anchor and the numerous types of conditions under which a catheter anchor might be applied, it is not uncommon for the needle to cause an injury to the patient which could be minor or significant. Older patients who have very thin skin (i.e. shallow epidermis and dermis layers) and minimal fat tissue in the subcutaneous layer of the skin (hypodermis) are particularly at risk for this type of injury especially for catheter insertions in the neck.
The depth of penetration into the skin is an important factor for patient comfort and for mitigating consequential damage such as excessive bleeding and tearing of the skin. The top two layers of the skin (the epidermis and dermis layers) are typically 2-4 mm in depth depending on the location on the body. Since the majority of the nerve endings lie at the junction of the epidermis and dermis layers, it is desirable to penetrate through the dermis layer and into the subcutaneous layer of the skin to avoid excessive discomfort and to reduce the risk of tearing the skin while the catheter anchor is in place. Penetrating the skin deep into the subcutaneous layer runs the risk of reaching the underlying muscle layer or bone depending on the insertion location, and excessive bleeding may occur due to the presence of larger blood vessels, veins, and arteries. The depth of the skin will also vary based on the age of the patient (due to decreased amounts of fat cells), the general health of the patient, and the body mass index of the patient. The skin in the neck, for example, is most frequently thinner than the skin in the chest. Therefore, it would be desirable to have a reliable penetration depth of the sharps to reduce the aforementioned negative consequences of a needle insertion, while maximizing the holding strength of the catheter anchor.
There have been numerous attempts to create alternative catheter anchors to the common sutured catheter anchor. One type uses an adhesive backed base which adheres to the patient's skin. While no needles or sharps are employed in this methodology, the drawbacks to this type of catheter anchor are significant. First, the adhesive can cause significant irritation to the skin of some patients. Second, removal of the adhered catheter anchor can cause significant damage to the patient's skin including tearing, and the removal process can be slow and painstaking, sometimes requiring the use of harsh chemicals. Third, adhesive-type catheter anchors are difficult to apply to wet, sweaty, or compromised skin. And the nature of the adhesive makes it not strong enough to hold most sizes of catheters on the patient's skin, making it suitable only for normally taped applications such as PICC lines. Some manufacturers of these adhesive-type catheter anchors acknowledge their weaknesses in their own instruction literature and recommend them only for use as a substitute for taped applications, making them unsuitable for catheter applications that normally require sutured catheter anchors.
Another type of catheter anchor employs a single-sided sharp or set of sharps that penetrate the skin and then re-emerge through the skin to lock into a plastic base which contains the anchoring mechanism for the catheter. U.S. Pat. No. 6,572,587 to Lerman et al. teaches one such method. U.S. Pat. No. 7,914,498 to Daniels, Jr. et al teaches another very similar method. In these examples and others, the exposed tip of the sharp which exits the skin to engage with the housing during insertion into the patient's skin becomes a potential risk for infection to the patient. While the tip of the sharp is exposed to the air (i.e. during the entire time the catheter anchor is attached to the patient) it may be exposed to contaminants. In order to remove the catheter anchor from the patient, the exposed portion of the sharp is drawn back underneath the skin and through the underlying tissue, potentially exposing the contaminated tip to the patient's bloodstream and increasing the risk of infection over the common suturing methodology.
One significant reason that sharp or needle-based catheter anchors have not been successful in supplanting the sutured catheter anchor is that none have solved the issue of eliminating or significantly reducing needlestick injuries. These types of catheter anchors can cause needlestick injuries either before, during, or after insertion, and this lack of full protection against needlestick injuries may be responsible for the lack of adoption of these methodologies. Lerman et al. describes the shortcomings of numerous prior art catheter anchors that fail to protect the operators and patients from needlestick injuries. Lerman et al. also claims to have reduced the risk of needlestick injury with its invention, but Lerman lacks any failsafe mechanism to prevent a needlestick injury during insertion or removal. Furthermore, once the contaminated device has been removed from a patient, there is nothing to prevent the operator or any other person who may come in contact with the device from deploying its sharps and potentially incurring a needlestick injury. In addition, there is no mechanism that prevents the reuse of the device which could cause grave injury after contamination. In fact, Lerman et al. even teaches that its device may be re-inserted into a patient's skin after removal as a methodology for anchoring if a catheter has to be repositioned. Daniels, Jr. et al. does not even mention the risks of needlestick injuries nor teaches any methodology to reduce the risk of needlestick injuries.